Bibcode
García López, Ramón J.; Israelian, Garik; Rebolo, Rafael; Bonifacio, Piercarlo; Molaro, Paolo; Basri, Gibor; Shchukina, Natalya
Referencia bibliográfica
In: Highlights of Astronomy, Vol. 12, as presented at the XXIVth General Assembly of the IAU - 2000 [Manchester, UK, 7 - 18 August 2000]. Edited by H. Rickman. San Francisco, CA: Astronomical Society of the Pacific, ISBN 1-58381-086-2, 2002, p. 413 - 415
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2002
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Descripción
Oxygen abundances have been derived in a sample of very metal-poor stars
using the O I triplet at λλ7771-5 Å and OH lines in
the near UV. A detailed NLTE analysis of iron lines has been carried out
for one of the observed stars, BD +23°3130, providing consistent
values of effective temperature and surface gravity that are in very
good agreement with independent estimates from the infrared flux method
and Hipparcos parallaxes, respectively. These parameters, especially the
higher gravity obtained with respect to previous analyses, reduce the
discrepancies claimed between the oxygen abundances determined from OH,
O I triplet and [O I] λ6300 Å lines, and give consistent
abundances to within 0.16 dex for BD +23°3130 ([Fe/H]NLTE
= -2.43). The oxygen abundances derived for this new sample confirm
previous findings for a progressive linear increase in the
oxygen-to-iron ratio with a slope -0.33±0.02 (including NLTE
corrections to the iron abundances for all the stars considered) from
solar metallicity to [Fe/H]~ -3, and [O/Fe] values as high as ~1.1 for
stars with [Fe/H]<~ -2.5. These results can be interpreted as
evidence for oxygen overproduction in the very early epoch of the
formation of the Galactic halo, possibly associated with supernova
events with very massive progenitor stars.